基于控制授粉技术的干旱诱导玉米籽粒败育的生理机制研究

Ear kernel number is one of the most important factors in maize yield determination. Kernel abortion occurs frequently in maize production caused by drought stress and led to yield low and unstability, and the increasing occurrence of drought is becoming a serious impact on maize production in China. However, the physiological mechanism of kernel abortion induced by drought is still not clear. In this study, by setting different treatments of drought stress to simulate different degree of field drought by pool-culture under controlled condition, and using control pollination technique to make maize ear bottom filaments does not pollination and induce the kernels located apical region to set, and at the same time the change of kernel carbohydrates, ethylene and polyamines, and the characteristics of kernel setting will be studied, and the characteristics of sink activity and plant assimilates accumulation (photosythetic productivity), transportion and distribution also will be studied under drought stress. Based on these, the variation characteristics of source, sink and flow and their effects on maize kernel assimilates supply and growth and development under drought stress will be clarified, and also including the variation characteristics of carbohydrate, ethylene and polyamines and their roles in maize kernel abortion under drought stress by systematical comparison between the set and aborted kernel located at ear apical region. Furthermore, the physiological mechanism of kernel abortion induced by drought from whole plant level and kernel metabolism level will be raised. Undoubtedly, it will be helpful to the index selection in maize drought resistance breeding and practical techniques innovation in maize production under drought stress.

穗粒数是决定玉米产量的最关键因子之一。生产中，干旱胁迫造成玉米籽粒败育经常发生，越来越频繁的旱灾已经成为我国玉米产量低而不稳的重要原因。然而，目前关于干旱诱导玉米籽粒败育的生理机制仍不明确。通过旱池设置不同干旱胁迫处理模拟不同程度的大田干旱，利用控制授粉技术使玉米果穗底部花丝不授粉，改变顶部籽粒的生育特性，进而通过系统比较研究果穗不同部位籽粒早期建成过程中的碳水化合物、乙烯和多胺的变化关系以及籽粒生育特性，干旱胁迫下籽粒库活性变化与植株的同化物生产性能、运输和分配特征以及果穗产量与产量构成的变化等，明确不同程度干旱胁迫下玉米源、库、流的变化关系及其在籽粒物质供应和生长发育中的作用，干旱胁迫条件下玉米籽粒早期建成过程中碳水化合物、乙烯和多胺的变化关系及其对籽粒败育的影响，进而从整株和代谢水平提出干旱诱导玉米籽粒败育的生理机制，以期为玉米抗旱育种指标选择和抗旱栽培技术创新提供参考。

穗粒数是决定玉米产量的关键因子，干旱胁迫造成玉米籽粒败育经常发生，近些年来越来越频繁的旱灾已经成为我国玉米产量低而不稳的重要原因。然而，目前关于干旱诱导玉米籽粒败育的生理机制仍不明确。本研究利用旱池设置不同干旱胁迫处理模拟不同程度的大田干旱，利用控制授粉技术设置玉米果穗底部花丝不授粉、中下部花丝推迟授粉等处理，改变籽粒的生育特性，同时利用玉米籽粒离体培养技术结合ABA模拟干旱，系统比较了玉米果穗不同部位籽粒早期建成过程中的碳水化合物、乙烯和多胺的变化关系以及籽粒生育特性，籽粒ABA变化特性与糖代谢关键酶活性（籽粒库活性）变化，以及植株叶片光合特性、不同器官的生长关系等。研究明确了干旱胁迫条件下叶片光合作用下降，植株各器官对光合碳同化物的竞争加剧，由于雌穗在竞争中的弱势在干旱条件下往往使果穗生长最易受到抑制，使开花吐丝间隔期（ASI）延长；底部不授粉和中下部花丝推迟授粉使顶部籽粒由败育变为正常结实，生育特性发生转变，而败育籽粒中酸性转化酶活性受抑制，败育籽粒糖浓度低，乙烯释放维持在高水平，进一步验证了不足的碳水化合物供应是玉米籽粒败育的根本原因；同时，明确了高浓度ABA不利于籽粒生长，早期ABA处理较中后期影响大，但是ABA处理的籽粒都没有发生败育，且中后期适宜浓度的ABA处理有利于籽粒灌浆，增加粒重。在以上研究基础上，从整株和代谢水平提出了干旱诱导玉米籽粒败育的生理机制，明确了玉米籽粒灌浆中后期适度干旱胁迫有利于促进籽粒灌浆增加粒重，选育ASI短的品种是抗御干旱等非生物逆境的重要途径。研究结果对于玉米抗旱育种和抗旱栽培具有重要意义。四年来，项目投入研究人员9名，按计划完成了研究任务。已发表研究论文5篇，其中SCI收录4篇；培养博士后1名、博士研究生4名、硕士研究生1名。